JP2018048853A - Rolling resistance evaluation device of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling resistance evaluation device of a tire capable of reducing the capacity of a power source for acquiring vibration amplitude and reducing the vibration and the fatigue damage of the entire device and the drum constituted member.SOLUTION: A rolling resistance evaluation device 10 of a tire includes: a load applying roll 44 having a surface simulating a road surface on which a tire 2 runs: a moving mechanism for alternately moving the load applying roll 44 in a proximal direction which is a direction proximate the tire 2 and in a separating direction which is a direction to separate from the tire 2; a load applying sensor 38; a position sensor 37; and a rolling resistance evaluation part 49 for comparing the phase difference deriving part 48 for deriving the phase difference with the variation of the applying load and the variation of the position of the load applying roll 44 based on the signals from the load applying sensor 38 and the position sensor 37 and the phase difference derived by the phase difference deriving part 48 and evaluating the rolling resistance of the tire to be the evaluation object, where two or more load applying roll 44 arranged side by side are smaller than the tire 2 in diameter.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a tire rolling resistance evaluation apparatus.

  One of the important measurement items in measuring the properties and performance of trucks, passenger cars and other vehicle tires is tire rolling resistance.

  The rolling resistance of the tire is a tangential force generated between the tire and the ground when the tire rolls on the ground. In a tire testing machine, the rolling resistance of a tire is measured as a tangential force generated between a test tire and a mating surface (for example, the surface of a load drum) that rotates in contact with the tire. That is, when a certain amount of radial force (load load Fz) is applied between the tire and the mating surface, a rolling resistance Fx corresponding to the load load Fz of the tire is generated, and the load load Fz and the rolling resistance are generated. The relationship with Fx is measured.

  Such a rolling resistance measurement method is defined by JIS D 4234 (passenger car, truck and bus tires—rolling resistance test method, 2009) as a method using a drum type tire running tester.

  As a rolling resistance tester of JIS standard, for example, the one shown in Patent Document 1 is known. In the rolling resistance measuring device of Patent Document 1, a tire is pressed against the outer peripheral surface of a cylindrically-shaped load drum (traveling drum), and a multi-component force detector of a spindle that supports the tire via a bearing causes x, The force and torque (moment) applied in the y and z axis directions are measured. The apparatus of Patent Document 1 is configured to measure the relationship between the load Fz in the axial direction of the tire and the rolling resistance Fx after correcting the interference between these component forces.

  However, in the rolling resistance measuring device of Patent Document 1, it takes time to measure the rolling resistance of one tire, and therefore it takes a lot of time to measure the rolling resistance of all the tires produced.

  In order to reduce the time required to measure the rolling resistance of a tire, Patent Document 2 discloses a technique for predicting the rolling resistance coefficient using a tire uniformity testing machine that inspects tire uniformity. It is known that rolling resistance is caused by energy loss when the tire rubber member is deformed during running of the tire and has a high correlation with the damping characteristics of the tire rubber member. Therefore, in Patent Document 2, a rolling resistance coefficient is obtained by exciting a tire with a drum provided in a tire uniformity testing machine and measuring a damping characteristic that appears as a phase difference between a drum displacement and a reaction force. A method has been devised. In the uniformity measurement process for testing all tires, a phase difference corresponding to the attenuation characteristic of each tire is measured, and abnormal tires whose rolling resistance coefficient values do not fall within the reference range are selected. In the selection of abnormal tires, the phase of the reference tire is calculated in advance by the method of Patent Document 2 with respect to the reference tire whose rolling resistance coefficient is within the reference value. By comparing the phase of the reference tire with the measured phase of the production tire, a case where the difference exceeds the allowable value is determined as a defective tire.

Japanese Patent Laid-Open No. 2003-4598 Japanese Patent Laying-Open No. 2015-232545

  However, in the method of oscillating the tire by vibrating the load drum of Patent Document 2, the mass of the load drum is large (in order to bring the tire deformation closer to the normal flat state, a load drum larger than the tire diameter has conventionally been used. In order to obtain a predetermined excitation amplitude, it is necessary to increase the capacity of the power source. In addition, the drum constituent member has problems of fatigue damage and vibration and fatigue of the entire apparatus.

  Therefore, the present invention has been made to solve the above-described problems. The capacity of the air cylinder as a power source for obtaining the excitation amplitude of the load drum is reduced, and the vibration of the entire apparatus and drum components are reduced. Another object of the present invention is to provide a rolling resistance evaluation apparatus that can reduce fatigue damage.

  The rolling resistance evaluation apparatus according to the present invention includes a load roll having a surface simulating a road surface on which a tire travels, a proximity direction that is a direction close to the tire, and a separation direction that is a direction away from the tire. A movement mechanism for alternately moving in the direction, a load sensor for detecting a load applied to the tire in a state where the surface of the load roll is in contact with the tire, and along the proximity direction and the separation direction A position sensor for detecting the position of the load roll in the determined direction, and the moving mechanism is controlled so that a load applied to the tire varies, and the load varies based on signals from the load sensor and the position sensor. And a phase difference deriving unit for deriving a phase difference between the load roll and a change in the position of the load roll, and the phase difference deriving unit for the reference tire A rolling resistance evaluation unit that compares the phase difference and the phase difference derived by the phase difference deriving unit for the tire to be evaluated, and evaluates the rolling resistance of the tire to be evaluated. It is a resistance evaluation apparatus, Comprising: Two or more said load rolls arranged side by side are smaller diameters than the said tire.

  In the present invention, by using a load roll having a smaller diameter than the tire, the mass of the load roll can be greatly reduced. Thereby, the capacity | capacitance of the motive power source for a load roll to obtain a predetermined excitation amplitude can be made small, and the vibration and fatigue damage of the whole apparatus and a moving mechanism can be reduced. By arranging two or more load rolls side by side, the tire can be brought close to the actual ground contact state, and the curvature at the time of deformation of the tire can be reduced.

  The load roll is preferably installed separately from a tire testing machine for testing the tire. By installing a load roll separately from the tire testing machine, tires can be easily used with the same specifications without changing the existing testing machine or by simply remodeling the existing testing machine to different testing machines of different manufacturers and models. A rolling resistance evaluation device can be installed.

  It is preferable that the load roll is installed separately from the running drum of the tire testing machine. As a result, it is possible to install a tire rolling resistance evaluation device without modifying an existing tire testing machine, particularly a tire uniformity testing machine, or by simply modifying an existing tire testing machine, particularly a tire uniformity testing machine. .

  There are two load rolls, and the center point of each of the load rolls is in contact with the tire and passes through the center point of a virtual circle having the same diameter as the outer diameter of the tire. It is preferable that it falls within the straight line.

  When the radial dimension of the two load rolls is increased, the distance between the centers of the two load rolls is increased, and the contact state between the load roll and the tire is greatly different from the actual ground contact state of the tire. Therefore, by placing the center point of the load roll between two straight lines that contact the tire and pass through the center point of a virtual circle having the same diameter as the outer diameter of the tire, The distance between the centers of the rolls can be reduced, and the tire can be brought closer to the actual ground contact state.

The moving mechanism has an air cylinder;
The load roll may apply an excitation force to the tire by switching the supply pressure to the air cylinder between a high pressure and a low pressure.

  Since the moving mechanism has an air cylinder, an inexpensive and simple power source can be obtained. Further, by switching the supply pressure to the air cylinder between a high pressure and a low pressure, the load roll can give a stable excitation force to the tire.

  In the present invention, by using a load roll having a smaller diameter than the tire, the mass of the load roll can be greatly reduced. Thereby, the capacity | capacitance of the motive power source for a load roll to obtain a predetermined excitation amplitude can be made small, and the vibration and fatigue damage of the whole apparatus and a moving mechanism can be reduced. By arranging two or more load rolls side by side, the tire can be brought close to the actual ground contact state, and the curvature at the time of deformation of the tire can be reduced.

1 is a schematic view of a tire rolling resistance evaluation device and a tire uniformity testing machine according to an embodiment of the present invention. It is sectional drawing which looked at the rolling resistance evaluation apparatus of the tire from the side. It is a top view of the rolling resistance evaluation apparatus of a tire. It is a front view of the rolling resistance evaluation apparatus of a tire. It is an air circuit diagram which drives an air cylinder. It is a plane sectional view showing the relation between a load roll and a tire. It is a plane sectional view showing the state where a load roll was pressed against a tire. It is a block diagram showing an electrical configuration of an evaluation device for tire rolling resistance It is the graph which showed typically the phase difference of the displacement of a load roll, and load amplitude. It is a side view which applied the rolling resistance evaluation apparatus to the tire with a small external dimension. It is the side view which applied the rolling resistance evaluation apparatus to the tire with a large external dimension. It is a side view of the rolling resistance evaluation apparatus of the tire which concerns on the modification 1. FIG. It is a front view of the rolling resistance evaluation apparatus of the tire which concerns on the modification 1. FIG. It is the side view which applied the rolling resistance evaluation apparatus of the tire which concerns on the modification 2 to the tire with a small external dimension. It is the side view which applied the rolling resistance evaluation apparatus of the tire which concerns on the modification 2 to the tire with a large external dimension.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the rolling resistance evaluation apparatus 10 (hereinafter simply referred to as “evaluation apparatus”) of the present embodiment performs a tire uniformity test (JIS D4233) for inspecting the uniformity in the circumferential direction of the tire 2. It is attached to a tire uniformity testing machine (TUM: Tire Uniformity Machine) 1 to be performed. Since the evaluation device 10 is not separately integrated with the tire uniformity testing machine 1 but is installed separately, a load roll 44 (44A, 44B), which will be described later, is installed separately from the traveling drum 4 of the tire uniformity testing machine 1. Yes. The evaluation device 10 is installed on the opposite side with the tire uniformity testing machine 1 and the tire 2 in between. The tire 2 has an annular shape and is rotatably supported by a tire shaft 3 extending in the vertical direction. The installation location of the evaluation device 10 is not particularly limited as long as it does not interfere with the traveling drum 4 of the tire uniformity testing machine 1, particularly the tire uniformity testing machine 1.

  The evaluation device 10 evaluates the rolling resistance of the tire 2 by bringing a load roll 44 (see FIG. 2) having a surface (outer peripheral surface) simulating a road surface on which the tire travels into contact with the tire 2. The evaluation device 10 is fixed to a fixing member 6 installed on the foundation 5 in the vertical direction.

  The evaluation apparatus 10 includes a standing wall 11 fixed to the fixing member 6 in a vertical direction (up and down direction in FIG. 2), a base frame 26 extending in a horizontal direction (left and right direction in FIG. 2) orthogonal to the standing wall 11, and a base And a housing 30 that moves horizontally on the frame 26.

  Referring also to FIG. 3, on the housing 30 side of the standing wall 11, the tip portion is coupled to the protruding wall portion 35 of the housing 30, and the air cylinder 13 that connects the standing wall 11 and the protruding wall portion 35 of the housing 30 is fixed. Has been. The air cylinder 13 is preferably disposed at a position where the load roll 44 is applied with a load near the center of the tire 2. The air cylinder 13 is disposed near the center of the load roll 44 in the height direction, and the air cylinder 13 constitutes a moving mechanism.

  The moving mechanism (air cylinder 13) moves the load roll 44 through the housing 30 in the proximity direction which is the direction approaching the tire 2 (right direction in FIG. 3) and the separation direction which is the direction away from the tire 2 (FIG. 3). (Middle, left) The air cylinder 13 has a pressure chamber 15 on the housing 30 side defined by the piston 14, and the housing 30 is moved via the piston rod 16 by switching the pressure of the pressure chamber 15. Along with the air cylinder 13, two springs 12 that connect the standing wall 11 and the back wall 34 of the housing 30 are disposed on the housing 30 side of the standing wall 11. The two springs 12 urge the housing 30 toward the standing wall 11 without hindering the movement of the load roll 44 by the air cylinder 13.

  FIG. 5 shows an air circuit 20 for driving the air cylinder 13. The pressure of the pressure chamber 15 of the air cylinder 13 is switched by an air circuit 20 connected to a pressure source 21. The air circuit 20 includes a high-pressure side high-pressure regulator 22 connected in parallel between a pressure source 21 and a second electromagnetic valve 25 connected to the air cylinder 13, and a low-pressure side low-pressure regulator 23. Yes. A first electromagnetic valve 24 is connected between the high pressure regulator 22 and the second electromagnetic valve 25, and high pressure or low pressure air is placed in the pressure chamber 15 of the air cylinder 13 by switching the first electromagnetic valve 24 from OFF to ON. It will be in the state which supplies.

  High pressure air is supplied to the pressure chamber 15 by turning off the second solenoid valve 25 with the first solenoid valve 24 turned on. Low pressure air is supplied to the pressure chamber 15 by turning on the second solenoid valve 25 with the first solenoid valve 24 turned on. When the first solenoid valve 24 and the second solenoid valve 25 are turned off from on, the supply of air to the pressure chamber 15 is stopped and the pressure chamber 15 becomes atmospheric pressure.

  Returning to FIG. 2, a pair of linear guide 27 rails linearly extending from the end of the base frame 26 on the standing wall 11 side to the tire 2 side end (right end in FIG. 2) on the upper surface of the base frame 26. 28 is fixed.

  The housing 30 rotatably supports the load roll 44 and reciprocates the load roll 44 with respect to the tire 2 at a constant frequency along the linear guide 27. Referring also to FIG. 4, the housing 30 has a vertically long box shape with an open front (front side in FIG. 4), and includes a bottom wall 31, an upper wall 32, a side wall 33, and a back wall 34 (see FIG. 3). And a protruding wall portion 35.

  A slider 29 that slides along the rail 28 of the linear guide 27 is provided on the lower surface of the bottom wall 31. Since the housing 30 is attached to the base frame 26 via the linear guide 27, the housing 30, that is, the load roll 44 can be prevented from being inclined. The displacement amount of the housing 30 that moves along the linear guide 27 is measured by a position sensor 37 fixed to the standing wall 11. In other words, the position sensor 37 detects the position of the load roll 44 in the direction along the approach direction and the separation direction to the tire 2 by measuring the amount of displacement of the housing 30. In this embodiment, a non-contact laser displacement meter is used as the position sensor 37, but a contact displacement meter or a vortex displacement meter may be used.

  On the lower surface of the bottom wall 31 and the upper surface of the upper wall 32, load cells 38 that are load sensors that detect a load applied to the tire 2 when the surface of the load roll 44 is in contact with the tire 2 are disposed. An upper roll fixing member 42 that fixes the upper ends of the two roll shafts 41 is attached to the upper load cell 38, and a lower end that fixes the lower ends of the two roll shafts 41 is attached to the lower load cell 38. A side roll fixing member 42 is attached. Each of the two roll shafts 41 rotatably supports the load roll 44 via a bearing 43. With these configurations, when the load roll 44 is crimped to the tread surface of the tire 2, the load is transmitted to the load cell 38 via the roll shaft 41 and the roll fixing member 42, and the load load applied to the tire 2 by the load cell 38 is reduced. It is measured. Since all the loads acting on the two load rolls 44 act on the load cell 38, the loads can be measured with high accuracy.

  The load roll 44 is a cylindrical member having an axial center extending in the vertical direction, and the outer peripheral surface of the load roll 44 is a simulated road surface for tire testing. FIG. 6 is a plan sectional view showing the relationship between the load roll 44 and the tire 2 in a state where the load roll 44 is in contact with the tire 2. The two load rolls 44 </ b> A and 44 </ b> B are arranged side by side, and the outer diameter of each of the load rolls 44 </ b> A and 44 </ b> B is smaller than the outer diameter of the tire 2. The minimum outer diameter of the load roll 44 is determined by the strength of the load roll 44 with respect to the load. In the present embodiment, the ratio between the outer diameter of the tire 2 and the outer diameter of the load rolls 44A and 44B is 5: 1. The two load rolls 44A and 44B have the same external dimensions (same shape), and the specific numerical values of the outer diameter dimensions of the load roll 44 are not particularly limited.

  Of the two load rolls 44, the distance L3 between the center point C2 of one load roll 44A and the center point C1 of the tire 2 is the center point C3 of the other load roll 44B and the center point C1 of the tire 2. Is equal to the distance L4. That is, the center point C2 of the load roll 44A and the center point C3 of the load roll 44B are located concentrically with the diamond 2. A midpoint C5 of a line L5 connecting a center point C2 of one load roll 44A and a center point C3 of the other load roll 44B is a center point C1 of the tire 2 and a center point C4 of a virtual circle 46 described later. Is located on the line L6 connecting the two.

  Furthermore, the center point C2 of one load roll 44A and the center point C3 of the other load roll 44B are in contact with the tire 2 and pass through the center point C4 of a virtual circle 46 having the same diameter. It arrange | positions so that it may fit between the two straight lines L7. The two load rolls 44A and 44B are arranged so that their outer peripheral surfaces are separated from each other.

  The evaluation device 10 further includes a phase difference deriving unit 48 and a rolling resistance evaluating unit 49. As shown in FIG. 8, the air cylinder 13, the position sensor 37, and the load cell 38 of the moving mechanism described above are connected to a phase difference deriving unit 48, and the phase difference deriving unit 48 is connected to a rolling resistance evaluating unit 49. The phase difference deriving unit 48 controls the air cylinder 13 so that the load applied to the tire 2 varies, and based on signals from the load cell 38 and the position sensor 37, the phase difference between the load variation and the load roll 44 position variation. Is derived. The rolling resistance evaluation unit 49 compares the phase difference derived by the phase difference deriving unit 48 for the reference tire with the phase difference derived by the phase difference deriving unit 48 for the tire 2 to be evaluated, and compares the phase difference of the tire 2 to be evaluated. Evaluate rolling resistance.

  Next, a method for evaluating the rolling resistance of the tire 2 using the evaluation device 10 of the present embodiment will be described. The rolling resistance evaluation test is performed after the traveling drum 4 is retracted from the tire 2 after the tire uniformity test using the traveling drum 4.

  In the evaluation device 10 of the present invention, the tire 2 is evaluated using a parameter called tan δ representing the damping characteristic of the tire rubber. For example, as a factor of tire rolling resistance, resistance due to energy loss (hysteresis loss) due to repeated distortion of tire rubber deformed by a load due to rotation is greatly affected. This hysteresis loss can be evaluated by tan δ. This δ of tan δ corresponds to the phase difference between strain and stress generated when a periodic external force is applied to the tire rubber. As the value of tan δ increases, the energy loss due to the deflection of the tire increases, and as a result, the rolling resistance also increases.

  Specifically, δ (phase difference) of tan δ is measured by alternately moving (vibrating) the above-described load roll 44 in the direction approaching and separating from the tire 2. In other words, when the load rolls 44 are moved alternately, a change in the load applied to the tire 2 is observed that is slightly ahead of the change in the position of the load roll 44. Therefore, by comparing the variation in the position of the load roll 44 with the variation in the load and calculating the phase shift between the two, the phase shift tan corresponds to the above-described tan δ. In the evaluation device 10 of the present embodiment, the rolling resistance of the tire 2 is evaluated based on whether or not the value of tan δ calculated in this way exceeds a predetermined threshold value.

  When the rolling resistance of the tire 2 is evaluated by the evaluation device 10, it is necessary to apply an excitation force to the tire 2 by moving the load roll 44 pressed against the tire 2 with respect to the tire 2. In order to alternately move the load roll 44 in the approaching direction and the separating direction, the supply pressure to the air cylinder 13 that drives the load roll 44 is switched between a high pressure and a low pressure. As a result, the load roll 44 applies a vibration force to the tire 2, and the load applied to the tire 2 fluctuates greatly.

  Specifically, in the initial state, the first solenoid valve 24 and the second solenoid valve 25 are off, and the pressure in the pressure chamber 15 of the air cylinder 13 is atmospheric pressure. At this time, since the spring 12 urges the housing 30 toward the standing wall 11, the load roll 44 is separated from the tire 2. In this state, the high pressure is introduced into the pressure chamber 15 by switching the first electromagnetic valve 24 on while the second electromagnetic valve 25 remains off, and the air cylinder 13 resists the urging force of the spring 12 and removes the housing 30 from the tire. Press toward 2. Thereby, the load roll 44 advances and is pressed against the tire 2 so that the load load measured by the load cell 38 becomes a predetermined load load (see FIG. 7).

  Next, a low pressure is introduced into the pressure chamber 15 by switching the second electromagnetic valve 25 from OFF to ON while the first electromagnetic valve 24 is ON, and the load roll 44 is retracted by the reaction force from the tire 2. That is, from the state in which the load roll 44 is pressed against the tire 2, the load roll 44 is moved backward in the counter-pressing direction to reduce the load load.

  Thereafter, the first electromagnetic valve 24 is kept on and the second electromagnetic valve 25 is switched on and off at a predetermined frequency, so that the load roll 44 and the tire 2 are kept in contact with each other while maintaining the contact state between the load roll 44 and the tire 2. Apply variable load to 2.

  At this time, a change in the position of the load roll 44 is measured by the position sensor 37, and a change in the load load is measured by the load cell 38. When the time-dependent fluctuation of the position of the load roll 44 and the fluctuation of the load applied as described above are extracted by extracting only the excitation frequency component using a filter or the like, a curve as shown in FIG. 9 is obtained.

  As shown in FIG. 9, with respect to the change curve of the roll displacement in the pressing direction applied to the tire, the change curve of the load load is recorded by being advanced by the phase difference δ due to the damping characteristic of the tire rubber. Therefore, the phase difference deriving unit 48 calculates the phase difference δ along the horizontal direction between the roll displacement change curve and the load change curve. In general, the phase difference between two signal waveforms is often calculated by obtaining a transfer function by FFT analysis.

  Based on the phase difference δ thus calculated, tan δ is calculated, and the rolling resistance of the tire 2 is evaluated based on whether the calculated tan δ exceeds a predetermined threshold value. Specifically, first, the phase difference δ is measured with respect to a reference tire having no abnormality in properties or characteristics. Next, the phase difference δ of the tire to be evaluated is measured. When there is a difference beyond the allowable range compared to the value of the phase difference δ of the reference tire, in other words, when the phase difference δ exceeds a predetermined threshold, the tire rolling resistance is greater than the standard value. I can judge. Therefore, when the phase difference δ exceeds a predetermined threshold, the rolling resistance evaluation unit 49 evaluates that the tested tire is a tire having an abnormal rolling resistance, and excludes the corresponding tire as necessary.

  When the calculated tan δ is equal to or less than a predetermined threshold (in other words, tan δ is a value within a predetermined range compared to the value of the phase difference δ of the reference tire), the rolling resistance evaluation unit 49 evaluates the tan δ. The target tire is evaluated as a tire with normal rolling resistance, and is treated as a tire that satisfies the product standards.

  When the rolling resistance evaluation test is completed, the first electromagnetic valve 24 and the second electromagnetic valve 25 are switched from on to off to release the pressure in the pressure chamber 15. Thereby, the pressure chamber 15 becomes atmospheric pressure, and the spring 12 urges and moves the housing 30 toward the standing wall 11, so that the load roll 44 is separated from the tire 2.

  If the evaluation apparatus 10 described above is used, tan δ having a high correlation with the rolling resistance of the tire can be obtained, and the rolling resistance of the tire can be easily evaluated based on the obtained tan δ. As a result, it is possible to accurately select tires having an abnormality in rolling resistance in a short time, and it is possible to inspect the rolling resistance of all manufactured tires.

[Features of tire rolling resistance evaluation apparatus of this embodiment]
The evaluation device 10 of the present embodiment has the following features.

  In the evaluation apparatus 10 of the present embodiment, by using the load roll 44 having a diameter smaller than that of the tire 2, the mass of the load roll 44 can be significantly reduced. Thereby, the capacity | capacitance of the motive power source for the load roll 44 to obtain a predetermined excitation amplitude can be made small, and the vibration and fatigue damage of the whole apparatus and a moving mechanism can be reduced. By arranging two or more load rolls 44 side by side, the tire 2 can be brought close to the actual ground contact state, and the curvature of the tire 2 when deformed can be reduced.

  In the evaluation apparatus 10 of the present embodiment, the load roll 44 is installed separately from each tire testing machine for testing the properties or performances of the tire including the tire uniformity testing machine, the tire balancer, and the traveling testing machine, so that the existing roll testing machine 10 is installed. The evaluation device 10 can be easily installed with the same specifications in various testing machines of different manufacturers and types without remodeling the testing machine or by simple modification of the existing testing machine.

  In the evaluation apparatus 10 of the present embodiment, the load roll 44 is installed separately from the traveling drum 4 of the tire uniformity tester 1 among the tire testers, so that the existing tire uniformity tester 1 is modified. The evaluation device 10 can be installed without any modification or by simple modification of the existing tire uniformity testing machine 1.

  In the evaluation apparatus 10 of the present embodiment, when the radial dimension of the two load rolls 44 increases, the distance between the centers of the two load rolls 44 increases, and the contact state between the load roll 44 and the tire 2 is determined by the tire. This is very different from the actual grounding condition of 2. Therefore, by placing the center point of the two load rolls 44 between the two straight lines that contact the tire 2 and pass through the center point of the virtual circle 46 having the same diameter and circumscribe the tire 2, The distance between the centers of the load rolls 44 can be reduced, and the tire 2 can be brought close to the actual ground contact state.

  In the evaluation apparatus 10 of this embodiment, since the moving mechanism includes the air cylinder 13, it can be an inexpensive and simple power source. Further, the load roll 44 can apply a stable excitation force to the tire 2 by switching the supply pressure to the air cylinder 13 between a high pressure and a low pressure.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  In the above-described embodiment, the evaluation device 10 is attached to the tire uniformity testing machine 1. However, the evaluation device 10 is the same even if attached to various tire testing machines that test the properties or performances of the tire such as a tire balancer and a running test machine. An effect can be obtained.

  Although the two load rolls 44 are used in the embodiment, the specific number is not particularly limited as long as there are a plurality of load rolls 44 such as three. Moreover, if the outer diameter dimension of the load roll 44 is smaller than the outer diameter dimension of the tire 2, the specific outer diameter dimension of the load roll 44 is not particularly limited.

  In the embodiment, the outer dimensions of the two load rolls 44 are the same, but a plurality of load rolls having different outer dimensions may be adopted. In the embodiment, the distance L3 between the center point C2 of one load roll 44A and the center point C1 of the tire 2 is between the center point C3 of the other load roll 44B and the center point C1 of the tire 2. It is equal to the distance L4. However, the present invention is not limited to this, and the distance L3 and the distance L4 may be different.

  In the above embodiment, the air cylinder 13 is used to apply the excitation force to the load roll 44 and the tire 2, but the present invention is not limited to this. For example, the same effect can be obtained by combining a hydraulic cylinder and a hydraulic circuit, and a ball screw and a servo motor. An example in which a ball screw and a servo motor are used will be described as a second modification described later.

  The evaluation apparatus 10 according to the present invention can be applied to various tires 2 having different outer diameter dimensions. In FIG. 10, the side view which applied the evaluation apparatus 10 to the tire 2 whose external dimension is smaller than the tire 2 used in the said embodiment is shown. At this time, the stroke of the air cylinder 13 is extended by moving the piston 14 of the air cylinder 13 toward the tire 2, and the load roll 44 is pressed against the tire 2. FIG. 11 shows a side view in which the evaluation device 10 is applied to the tire 2 having a larger outer dimension than the tire 2 used in FIG. At this time, the stroke of the air cylinder 13 is shortened by moving the piston 14 of the air cylinder 13 toward the fixing member 6, and the load roll 44 is pressed against the tire 2.

<Modification 1>
In the embodiment, the load cell is used as a load sensor that measures the load applied to the tire 2 when the load roll 44 is pressed against the tread surface of the tire 2. However, in the evaluation apparatus 10 according to Modification 1 shown in FIGS. 12 and 13, the strain gauge 51 is used as a load sensor instead of the load cell. Since the configuration of the evaluation device 10 other than this is the same as that of the above-described embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

  In the first modification, notches 52 (52a, 52b) are provided at both upper and lower ends of the roll shaft 41. One notch 52a at the upper end and the lower end is opposed to the back wall 34 of the housing 30, and the other notch 52b is provided on the opposite side of the notch 52a with the center of the roll shaft 41 in between. Yes. By attaching a strain gauge 51 to each notch 52, the load applied to the tire 2 can be measured.

<Modification 2>
In the embodiment, the evaluation device 10 is directly fixed to the fixing member 6. However, the present invention is not limited to this, and the evaluation device 10 may be installed on the fixed member 6 so as to be movable with respect to the tire 2. Specifically, as shown in FIGS. 14 and 15, the evaluation apparatus 10 is installed on a base portion 56 fixed to the fixing member 6 via a linear guide 27. At this time, the evaluation device 10 is moved with respect to the tire 2 by a ball screw 58 driven by a servo motor 57 fixed to the fixing member 6. Thereby, the evaluation apparatus 10 can be applied to various tires 2 having different outer dimensions.

DESCRIPTION OF SYMBOLS 1 Tire uniformity tester 2 Tire 10 Rolling resistance evaluation apparatus 12 Spring (movement mechanism)
13 Air cylinder (movement mechanism)
37 Position sensor 38 Load cell (load sensor)
44 Load roll 46 Virtual circle 48 Phase difference deriving unit 49 Rolling resistance evaluation unit

Claims (5)

A load roll having a surface simulating a road surface on which the tire travels;
A moving mechanism for alternately moving the load roll in a proximity direction that is a direction close to the tire and a separation direction that is a direction away from the tire; and
A load sensor for detecting a load applied to the tire in a state where the surface of the load roll is in contact with the tire;
A position sensor for detecting a position of the load roll in a direction along the proximity direction and the separation direction;
A phase difference that controls the moving mechanism so that the load applied to the tire varies and derives a phase difference between the load variation and the load roll position variation based on signals from the load sensor and the position sensor. A derivation unit;
Roll for evaluating the rolling resistance of the tire to be evaluated by comparing the phase difference derived by the phase difference deriving unit for the reference tire with the phase difference derived by the phase difference deriving unit for the tire to be evaluated A resistance evaluation unit;
A rolling resistance evaluation apparatus for tires equipped with
A rolling resistance evaluation apparatus for a tire, wherein two or more load rolls arranged side by side have a smaller diameter than the tire.   The tire rolling resistance evaluation apparatus according to claim 1, wherein the load roll is installed separately from a tire testing machine that tests the tire.   The tire rolling resistance evaluation apparatus according to claim 2, wherein the load roll is installed separately from a running drum of the tire testing machine.   There are two load rolls, and the center point of each of the load rolls is in contact with the tire and passes through the center point of a virtual circle having the same diameter as the outer diameter of the tire. 4. The tire rolling resistance evaluation device according to claim 1, wherein the tire rolling resistance evaluation device falls within a straight line. The moving mechanism has an air cylinder;
5. The tire rolling resistance evaluation apparatus according to claim 1, wherein an excitation force is applied to the tire by switching a supply pressure to the air cylinder between a high pressure and a low pressure.

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